﻿<!DOCTYPE html>

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8" />
    <title></title>

    <style type="text/css">
        .header{
            padding:10px 0;
            background-color:green;
        }

        .middle {
            top: 10px;
            /*bottom: 10px;*/
            height: calc(100vh - 80px);
            background-color: red;
        }

        .footer {
            padding: 10px 0;
            background-color: green;
        }
    </style>
</head>
<body>
    <div class="header">

    </div>

    <div class="middle">

    </div>

    <div class="footer">

    </div>
</body>
</html>